2. Outline
• A Brief History of Radiation
• What is Radiation?
• Types & Sources of Radiation
• Radiation Dose
• Biological Effects of Radiation
• Radiation Dose Limits & Dosimetry
• ALARA Philosophy – Protecting Yourself from Radiation
• Signage & Postings
• Security of Radioactive Material
3. A Brief History of Radiation
• Wilhelm Roentgen
◦ 1895 – Discovery of X-rays
4. • The history of radiation biology goes back almost
as far as the discovery of X-rays
1911
First Report Linking
X-rays to Cancer In
Physicians
1904
First Human Death
From X-ray Reported
1896
Elihu Thompson
Does Experiments
On X-ray Burns
1895
Roentgen
Discovered
X-rays
1901
Rollins Shows
X-rays Are Lethal
To Animals
6. What is Radiation?
• Transfer of energy through space
• Radiation can be ionizing or non-ionizing
◦ Ionizing radiation can knock electrons off of an
atom
++
++
-
Nucleus
(protons + neutrons)
Electron
-
-
-
-
7. Types & Sources of Radiation
• Machine Produced
◦ X-ray, CT, Cath Lab, etc
◦ Linear Accelerators
◦ Other particle accelerators
• Radioactive Materials
◦ Nuclear Medicine
◦ Radiation Therapy
◦ The Environment
◦ YOU!
8. How Does Radiation Go Away?
• Machine Produced
◦ TURN IT OFF!!!
• Radioactive Materials
◦ Radioactive Decay
9. Not All Radiation Is Created Equal
• Particles
◦ Alpha, beta, protons, neutrons
• Gamma & X-rays
• Hazard is dependent on
◦ Type
◦ Quantity
◦ Energy
◦ Matter
-
ɣ
α
β
Paper Plastic Lead
10. Exposure Sources for Effective Dose
Computed Tomography
24%
Nuclear Medicine
12%
Interventional
Fluoroscopy
7%
Conventional
Radiography
5%
Consumer
2%
Occupational
0%
Industrial
0%
Radon & Thoron
37%
Space
5%
Internal
5%
Terrestrial
3%
Data from NCRP Report 160
Background – 310 mrem
Medical – 300 mrem
11. • Dose is defined as the energy deposited per unit mass
◦ 1 J/kg = 1 Gray
• Measured in units of
◦ Gy absorbed dose
◦ Sv dose equivalent
◦ 100 rad = 1 Gy
◦ 100 rem = 1 Sv
1 kg
Incident
Radiation
1.6 x 10-19 Joules = 1 eV
What is Dose?
12. Non-Stochastic vs. Stochastic
• Non-Stochastic Effects (Non-Probabilistic)
◦ A threshold dose exists!
◦ Erythema
◦ Epilation
◦ Dermal Necrosis
• Stochastic Effects (Probabilistic)
◦ A threshold does (might) not exist – LNT
◦ Most common stochastic effect – cancer
◦ Stochastic effects have a latency period
◦ Most cancers ~ 20 – 40 years Dose
Risk
15. Dose Limits & Dosimetry
Annual Limit
Whole Body (TEDE) 5,000 mrem 50 mSv
Extremities & Skin (SDE) 50,000 mrem 500 mSv
Lens of Eye 15,000 mrem 150 mSv
Gestational Limit
Declared Pregnant Workers 500 mrem 5 mSv
Limits
Members of the Public 100 mrem* 2 mrem in any 1 hour
* Limit goes to 500 mrem when source is an individual administered unsealed byproduct material
16. Dosimeters
• May be issued monthly or
quarterly
• Only wear your badge!
• Store in a low background area
• Wear outside of your lead, if
applicable
17. ALARA
• As Low As Reasonably Achievable
◦ Reasonable efforts should be made to keep occupational doses as far below regulatory limits
as possible
• Fundamentals of radiation protection
◦ Time, Distance, & Shielding
• Sources of exposure in a hospital
◦ Radiology (X-Ray, CT, NM)
◦ Radiation Therapy
◦ Cath Lab, GI Lab, Pain Clinics, etc
Time
Distance
Shielding
19. Shielding
• Some considerations
◦ What types of radiation are you shielding?
◦ What is the energy and activity?
◦ What shielding material do you have available?
• Shielding should be placed as close to the source as possible
◦ Isotropic vs. collimated beam
ɣ
α
β
Paper Plastic Lead
22. Security of Radioactive Material
• Radioactive materials should be stored in a way
to prevent unauthorized removal
◦ Locked room – “Hot Lab”
◦ Locked cabinets
◦ Under constant surveillance if not secured
• Increased controls
◦ Background Checks / Fingerprints
◦ Security Escorts
◦ Video surveillance
• Lost or stolen radioactive materials must be
reported to appropriate authorities!
23. Closing Thoughts
• Radiation is an extremely useful tool in medicine
• Should be used and handled with appropriate safety measures
◦ Time
◦ Distance
◦ Shielding
• Report conditions you believe are unsafe
• Ask questions!
• Excellent resource is your RADIATION SAFETY OFFICER